Fructose, also known as fruit sugar, is a mono-saccharide constituting one-half of the sucrose molecule. Inasmuch as the sweetness of fructose is about 1.3 to about 1.8 times that of crystalline sucrose, fructose is a commercially attractive sweetener as an alternative for sucrose and has been produced commercially for that purpose for a considerable time period. In food formulations, fructose is frequently used for special dietary purposes, e.g. to reduce the calorie content of desserts, jams and other industrially prepared products, to control blood sugar levels, and the like.
Methods for crystallization of fructose from aqueous or alcoholic solutions are known. Some such methods are described in Hara et al. U.S. Pat. No. 3,704,168 and in Forsberg et al. U.S. Pat. No. 3,883,365.
More specifically, Hara et al. U.S. Pat. No. 3,704,168 is directed to a crystallization process where fructose crystals are derived from a mixed liquid polyhydric and monohydric alcohol medium which is supersaturated with fructose at a temperature of -20.degree. C. to 70.degree. C. Forsberg et al. U.S. Pat. No. 3,883,365, on the other hand, describes a fructose crystallization method where a saturated aqueous fructose solution is adjusted to a pH value of 4.5 to 5.5 and cooled, optionally by a concurrent evaporation of the water present, to bring about crystallization of fructose.
It has now been discovered, however, that the crystallization of fructose can be expedited by crystallizing fructose from a solution at a substantially constant temperature while the solvent is removed from the solution by azeotropic evaporation.